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Can you reinstall 2008R2 Domain Controller to domain if AD schema has been upgraded to 2012 R2?

    Question

  • Hello,

    We have a single-domain forest. AD schema version in Windows Server 2008 R2. Domain Functional Level and Forest Functional Levels are also 2008 R2.

    I'm just wondering is it supported option to re-promote 2008R2 Domain Controller to domain if AD schema has already been extended to Windows Server 2012 R2? DFL/FFL levels are still in Windows Server 2008 R2.

    I'm thinking about different rollback options incase some application emerges after 2012 R2 AD schema upgrade which refuses to work with 2012 R2 Domain Controller. I know that AD schema version cannot be reversed without Forest Recovery, but re-promoting 2008 R2 Domain Controllers could give more time to software developers to fix the application.

    Thursday, January 5, 2017 1:41 PM

Answers

  • Once the DFL is raised to Windows Server 2012, you cannot promote a Windows Server 2008 R2 domain controller. But even if the schema is updated for Server 2012, as long as the DFL is still Windows Server 2008 R2, you can promote a W2k8 R2 DC.

    Richard Mueller - MVP Enterprise Mobility (Identity and Access)

    • Proposed as answer by Thameur BOURBITAMVP Thursday, January 5, 2017 2:43 PM
    • Marked as answer by weedee Thursday, January 5, 2017 3:38 PM
    Thursday, January 5, 2017 2:31 PM

All replies

  • Once the DFL is raised to Windows Server 2012, you cannot promote a Windows Server 2008 R2 domain controller. But even if the schema is updated for Server 2012, as long as the DFL is still Windows Server 2008 R2, you can promote a W2k8 R2 DC.

    Richard Mueller - MVP Enterprise Mobility (Identity and Access)

    • Proposed as answer by Thameur BOURBITAMVP Thursday, January 5, 2017 2:43 PM
    • Marked as answer by weedee Thursday, January 5, 2017 3:38 PM
    Thursday, January 5, 2017 2:31 PM
  • As always Mr. Mueller, I greatly appreciate your response. Thank you for clarifying.
    Thursday, January 5, 2017 3:39 PM